1. Field of the Invention
The present invention is related to networks and, in particular to physical layer functions of networks.
2. Background Information
The term “network fabric” describes the physical structure of a network. Communication channels are interwoven from port to port such that network devices can be connected together to exchange information. Communications take place in many networks today in accordance with the well-known Open System Interconnection (OSI) reference model.
The OSI reference mode consists of seven layers, each of which specifies particular network functions such as addressing, flow control, error control, encapsulation, and reliable message transfer. For example, the physical layer (Layer 1) is closest to the transmission media technology (e.g., fiber-optic, copper) and is responsible for electrical, optical, mechanical requirements for connecting to the media. As such, the physical layer is responsible for voltages, currents, impedances, pin configurations, and handshaking procedures utilized by network elements.
The physical layer deals with signaling. Signaling generally concerns how the network controls access to the transmission media by network elements. For example, the physical layer translates logical “ones” and logical “zeros” into electrical or optical signals and places the signals onto the network transmission media for extraction or sampling by destination network elements. Translation of logical “ones” and logical “zeros” into electrical or optical signals is sometimes referred to as “encoding.”
The physical layer also deals with topology and hardware. Topology is the physical layout of devices and media within a network and hardware includes the physical layer devices (or nodes). Common network topologies include a linear bus topology, a star bus topology, a ring topology, and a mesh topology, in which devices are connected to a bus in a linear, star, ring, or mesh arrangement, respectively. Physical layer devices also deal with basis signaling. Common physical layer devices include drivers, receivers, transceivers, and similar devices.
Today's high-speed buses are capable of operation in the Gigahertz (GHz) range. However, current network fabric physical functions tend to be limited in their support communication between processes and devices across the transmission media at such high frequencies.